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				.\" Copyright (c) 2016 The FreeBSD Foundation, Inc.
				.\" All rights reserved.
				.\"
				.\" This documentation was written by
				.\" Konstantin Belousov <kib@FreeBSD.org> under sponsorship
				.\" from the FreeBSD Foundation.
				.\"
				.\" Redistribution and use in source and binary forms, with or without
				.\" modification, are permitted provided that the following conditions
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				.\"
				.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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				.\" $FreeBSD$
				.\"
				.Dd September 23, 2016
				.Dt THR_WAKE 2
				.Os
				.Sh NAME
				.Nm thr_wake
				.Nd wake up the suspended thread
				.Sh LIBRARY
				.Lb libc
				.Sh SYNOPSIS
				.In sys/thr.h
				.Ft int
				.Fn thr_wake "long id"
				.Sh DESCRIPTION
				.Bf -symbolic
				This function is intended for implementing threading.
				Normal applications should use
				.Xr pthread_cond_timedwait 3
				together with
				.Xr pthread_cond_broadcast 3
				for typical safe suspension with cooperation of the thread
				being suspended, or
				.Xr pthread_suspend_np 3
				and
				.Xr pthread_resume_np 3
				in some specific situations, instead.
				.Ef
				.Pp
				Passing the thread identifier of the calling thread
				.Po
				see
				.Xr thr_self 2
				.Pc
				to
				.Fn thr_wake
				sets a thread's flag to cause the next signal-interruptible sleep
				of that thread in the kernel to fail immediately with the
				.Er EINTR
				error.
				The flag is cleared by an interruptible sleep attempt or by a call to
				.Xr thr_suspend 2.
				This is used by the system threading library to implement cancellation.
				.Pp
				If
				.Fa id
				is not equal to the current thread identifier, the specified thread is
				woken up if suspended by the
				.Xr thr_suspend
				system call.
				If the thread is not suspended at the time of the
				.Nm
				call, the wake is remembered and the next attempt of the thread to
				suspend itself with the
				.Xr thr_suspend 2
				results in immediate return with success.
				Only one wake is remembered.
				.Sh RETURN VALUES
				.Rv -std thr_wake
				.Sh ERRORS
				The
				.Fn thr_wake
				operation returns these errors:
				.Bl -tag -width Er
				.It Bq Er ESRCH
				The specified thread was not found or does not belong to the process
				of the calling thread.
				.El
				.Sh SEE ALSO
				.Xr ps 1 ,
				.Xr thr_self 2
				.Xr thr_suspend 2 ,
				.Xr pthread_cancel 3 ,
				.Xr pthread_resume_np 3 ,
				.Xr pthread_suspend_np 3
				.Sh STANDARDS
				The
				.Fn thr_suspend
				system call is non-standard and is used by
				.Lb libthr
				to implement
				.St -p1003.1-2001
				.Xr pthread 3
				functionality.